Lecture 10: "Mr Darwin's Hypotheses"
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1
Outline
1.  Wallace’s path to a theory
2. Wallace’s and Darwin’s paths converge
3.  The race to the Origin of Species
4.  How to explain the convergence:
•  How common interests, ideas and influences
led two very different men to almost
exactly the same theory….
2
Taking stock: the situation in 1855
•  Darwin has been at work on his species theory for 17
years
•  Wallace has been searching for a species theory for 10
years
•  Wallace publishes “the Sarawak law”, which strongly
implies the evolution of species
•  Lyell is impressed with Wallace’s paper and shows it to
Darwin, who writes to congratulate Wallace, telling him
that they seem to be thinking along similar lines….
•  And, urged on by Lyell, Darwin starts work – at last! –
on a “big book” to be called Natural Selection
3
And three years later, in 1858
•  Darwin is roughly 2/3 of the way through Natural
Selection
•  And Wallace is on the island of Ternate in the
Moluccas, still working away on the species problem
•  …when he is struck down by a bout of “intermittent
fever” (malaria), which “prostrated me for several hours
during the day during the cold and succeeding hot fits”
•  And then this happened….
4
“..something led me to think of Malthus..”
“I was then [February, 1858] living at Ternate in the Moluccas, and
was suffering from a rather severe attack of intermittent fever,
which prostrated me for several hours every day during the cold
and succeeding hot fits…
…During one of these fits, while again considering the problem of
the origin of species, something led me to think of Malthus’ Essay
on Population (which I had read about ten years before), and the
“positive checks” – war, disease, famine, accidents, etc. – which he
adduced as keeping all savage populations nearly stationary…
…It then occurred to me that these checks must also act upon
animals, and keep down their numbers; and as they increase so
much faster than man does, while their numbers are always very
nearly or quite stationary, it was clear that these checks in their
case must be far more powerful, since a number equal to the
whole increase must be cut off by them every year.”
5
Wallace’s Malthusian “Eureka!” moment
“While vaguely thinking how this would affect any species, there
suddenly flashed upon me the idea of the survival of the fittest –
that the individuals removed by these checks must be, on the
whole, inferior to those that survived. Then, considering the
variations continuing occurring in every fresh generation of
animals or plants, and the changes of climate, of food, of enemies
always in progress, the whole method of specific modification
became clear to me, and in the two hours of my fit I had thought
out the main points of the theory. That same evening I sketched
out a draft of a paper; in the two succeeding evenings I wrote it
out, and sent it by the next post..” where exactly?
Where did he send it??
6
Oops!!
“While vaguely thinking how this would affect any species, there
suddenly flashed upon me the idea of the survival of the fittest –
that the individuals removed by these checks must be, on the
whole, inferior to those that survived. Then, considering the
variations continuing occurring in every fresh generation of
animals or plants, and the changes of climate, of food, of enemies
always in progress, the whole method of specific modification
became clear to me, and in the two hours of my fit I had thought
out the main points of the theory. That same evening I sketched
out a draft of a paper; in the two succeeding evenings I wrote it
out, and sent it by the next post to Mr. Darwin.” H
He sent it to Darwin!!
7
“Your words have come true with a
vengeance…”
“My dear Lyell
Some year or so ago, you recommended me to read a paper by
Wallace in the Annals, which had interested you & as I was writing to
him, I knew this would please him much, so I told him. He has to day
sent me the enclosed & asked me to forward it to you. It seems to
me well worth reading. Your words have come true with a vengeance
that I shd. be forestalled. You said this when I explained to you here
very briefly my views of “Natural Selection” depending on the
Struggle for existence.— I never saw a more striking coincidence. if
Wallace had my M.S.sketch written out in 1842he could not have
made a better short abstract! Even his terms now stand as Heads of
my Chapters.”
Darwin, letter to Lyell, 18 June 1858
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And now, events move swiftly…
•  Darwin receives Wallace’s paper in June 1858, and
writes seeking Lyell’s advice on what to do
•  Lyell and Joseph Hooker take over. They
–  ask Darwin for copies of dated manuscripts (including letters)
that establish his priority in the discovery of the principle of
natural selection
–  arrange for the reading of a joint paper comprising these
manuscripts plus Wallace’s paper, –  at a meeting of the Linnæan Society of London in July 1858
–  write to Wallace to tell him what they’ve done •  Darwin abandons his incomplete manuscript of Natural
Selection, and sits straight down to write On the
Origin of Species
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Darwin/Wallace paper, 1858
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But how will Wallace react?
“My dear Sir
I beg leave to acknowledge the receipt of your letter of July last,
sent me by Mr. Darwin, & informing me of the steps you had
taken with reference to a paper I had communicated to that
gentleman. Allow me in the first place sincerely to thank yourself
& Sir Charles Lyell for your kind offices on this occasion, & to
assure you of the gratification afforded me both by the course
you have pursued, & the favourable opinions of my essay which
you have so kindly expressed. I cannot but consider myself a
favoured party in this matter….”
Wallace, letter to Joseph Hooker, 6 October 1858
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Wallace continues…
“…It would have caused me much pain & regret had Mr.
Darwin’s excess of generosity led him to make public my
paper unaccompanied by his own much earlier & I doubt
not much more complete views on the same subject, & I
must again thank you for the course you have adopted,
which while strictly just to both parties, is so favourable
to myself.”
Wallace, letter to Joseph Hooker, 6 October 1858
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Darwin’s reaction: Phew!
“My dear Sir
I was extremely much pleased at receiving three days ago your
letter to me & that to Dr. Hooker. Permit me to say how heartily
I admire the spirit in which they are written. Though I had
absolutely nothing whatever to do in leading Lyell & Hooker to
what they thought a fair course of action, yet I naturally could
not but feel anxious to hear what your impression would be. I
owe indirectly much to you & them; for I almost think that Lyell
would have proved right & I shd. never have completed my larger
work, for I have found my abstract hard enough with my poor
health, but now thank God I am in my last chapter, but one….”
Darwin, letter to Wallace, January 25th 1859
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14
Aftermath
•  On his return to England in 1862, Wallace immediately
played an active role in developing & defending the
theory of evolution by natural selection
•  He continued to contribute actively to the development
of evolutionary biology
•  As we shall see, he came to differ with Darwin on
several important points
•  But he always gave Darwin the lion’s share of the
credit for their theory
•  And he even promoted use of the term “Darwinism” (!)
15
“Simultaneous discoverers”
•  Darwin and Wallace are
recognized as co-founders of
one of the great theories in
modern science
•  Their near-simultaneous
discovery can tell us a lot
about the nature of creative
steps in science, as well as
about the kinds of factors
that shaped the modern
theory of evolution at its
inception
16
“Creative steps” in science
Question:
What are some candidate key
ingredients to the making of
creative steps in science?
17
Candidate ingredients
•  New actors
–  Fresh viewers
•  New observations
–  Fresh things to be seen
•  New orientations
–  Fresh perspectives from which to see
•  New connections for old ideas
–  Fresh contexts in which to interpret what is being
seen
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New actors
Darwin
Wallace
•  A young man when he made
his discovery
•  Relatively well-trained
•  Familiar with transformist
ideas (from Lamarck, & his
grandfather)
•  Once he’d hit upon his
discovery, Darwin proceeded
very cautiously; he had a
growing professional
reputation, a secure position
in London society, and a
young family to think about….
•  A young man when he made
his discovery
•  Largely self-taught
•  Familiar with transformist
ideas (largely from the
Vestiges)
•  Once he’d hit upon his
discovery, he proceeded
apace; he had few influential
scientific friends, a reputation
to make and no family
responsibilities to think
about…
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New Observations
Darwin
Wallace
•  Naturalist & collector
•  Naturalist & collector
•  Major voyage of discovery
•  Major voyages of discovery
•  Collected many new species
across large (dis)continuous
area
•  Collected many new species
across large (dis)continuous
area
•  Saw meaningful patterns in
the geological & geographical
distribution of species
•  Saw meaningful patterns in
the geological & geographical
distribution of species
20
New orientations
Darwin
Wallace
•  had been trained in natural
theology, and took some time
to break with Paley’s natural
theology
•  was largely self-trained; he
had a penchant for radical
ideas and little investment in
natural theology
•  was greatly influenced by the
new geology (especially Lyell),
and was willing to think in
naturalistic terms almost as
soon as he was in the field
“on his own”
•  was greatly influenced by new
thinking in natural history,
including both Lyell’s geology
and the Vestiges of the
Natural History of Creation
21
New connections for old ideas
Darwin
Wallace
•  Saw domesticated plants &
animals as an important
source of insights into the
mechanism of descent with
modification
•  Saw domesticated plants &
animals as illustrating, not
how evolution might work but
what happens when the laws
of evolution are suspended
•  saw in Malthus a key to
understanding the role of the
struggle for existence in the
the natural world
•  saw in Malthus a key to
understanding the role of the
struggle for existence in the
the natural world
22
Converging Paths Darwin
•  Victorian naturalist
Wallace
•  Victorian naturalist
•  Inveterate collector
•  Inveterate collector
•  Voyage of exploration
•  Voyages of exploration
•  Interested in geological
& geographical
distribution
•  Interested in geological
& geographical
distribution
•  Read Malthus and
immediately saw its
relevance
•  Read Malthus, and
eventually saw its
relevance
23
What does this tell us about
“simultaneous discoveries” in science?
•  Simultaneous discoveries are (relatively) common in
science, because independent discoveries, while
independent of one another, are never independent of
a common scientific/cultural context
•  Scientific contemporaries often share similar
–  Experiences, theoretical sources, challenges, observations •  In short, simultaneous discoveries happen because
scientists don’t work in a social vacuum; they work in
overlapping and extensively shared networks of
intellectual, personal and social practice
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Darwin & Wallace
Convergence and Divergence? Darwin Wallace
•  Gentleman naturalist
Artisan naturalist
•  ‘Conservative revolutionary’
Consistently radical
leanings
•  Social networker
A loner
•  Reputation as “great man” 25
Mixed reputation
Wallace’s education
•  Left school at 13
•  Extensively self-taught
•  Attended ‘halls of science’ and mechanics’ institutes,
institutions of informal education that were also places
where radical ideas (in science, in politics, in religion)
flourished in early-Victorian society
26
Wallace’s radical causes
Early career (up to 1860):
–  phrenology
–  mesmerism
–  transformism (early fan of Vestiges)
Later career (after 1860):
–  Spiritualism (mediums, ‘table-turning’, etc.)
–  socialism (including land nationalization)
–  women’s suffrage
27
I’m a bit of
a radical
I never
really
wanted
to rock
the boat
Siimilar, but
different?
1858
joint
paper
I’m from a
distinguished
family of Whigs
(liberals)
I was never
very happy
being in the
boat in the
first place
So…what have we learnt?
•  Darwin and Wallace were genuinely
‘joint’ founders of the theory of
evolution by natural selection
•  They came to (essentially) the same idea
through remarkably parallel biographical
experiences
•  Nevertheless, each was ‘his own man’;
and after 1859, they would disagree on
many specific issues
29
A lesson for today?
•  Nonetheless, the way in which they
handled their joint ownership of modern
evolutionary theory was exemplary.
•  They never, ever
–  Disputed each other’s priority to the theory
–  Grumbled about the credit the other
received for the discovery
–  Became embittered rivals
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How amazing is that?!!
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STS.009 Evolution and Society
Spring 2012
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